Cell surface glycans are critical for interactions that initiate many enteric infections. This new grant application proposes translational studies to test the hypothesis that the complex interactions between glycan expression, neonatal development and human milk oligosaccharides affect neonatal enteric infections. Characterization of a rotavirus strain that almost exclusively infects neonates in India and new data that human rotaviruses can initiate infection by binding to histo blood group antigens (HBGAs) provide the foundation for this study. We propose: (1) to characterize intestinal glycans that are novel binding partners in rotavirus infectivity by analyzing the interactions between a rotavirus strain that infects neonates and glycans with the Gal?1-4GlcNAc motif including H type II HBGA, and (2) to determine the role of bioactive components of breast milk such as human milk oligosaccharides (HMO) and functional antibodies that competitively bind to the virus and block viral binding to intestinal glycans in protection from neonatal rotavirus infection and disease. Fo the first goal, we will identify critical glycan partners that bind to the neonatal rotavirus strai and are required for rotavirus infectivity. The second goal will be achieved by studying samples to be collected from neonates and their mothers in a nursery where incidence of infection is reproducibly high (nearly 50%). We predict that (a) structural analogues to intestinal glycans in breast milk play a protective role in neonatal infections by competitively inhibiting the binding o the pathogen to these glycans or (b) functional antibodies in breast milk inhibit the binding of th virus to glycans. A multidisciplinary team with expertise in epidemiology and field studies of enteric infection in children including neonates, molecular virology and viral pathogenesis, and in glycobiology and human milk oligosaccharides, will apply technological advances in glycobiology and human intestinal organoids to obtain new fundamental data on glycan expression in neonates and on whether human milk bioactive components specifically block neonatal viral infection. The information from this study may discover the first correlate of protection for rotavirus and will provide mechanistic insight into glycan expression during intestinal development of the neonate. This is likely to be significant and relevant to other neonatal infections or disease conditions where glycans play a significant role.